Mail FAIL Connect to mail servers ERROR: I could not complete a connection to any of your mailservers!

mail.xb360.nl: Timed out [Last data sent: [Did not connect]]

If this is a timeout problem, note that the DNS report only waits about 30 seconds for responses, so your mail may work fine in this case but you will need to use testing tools specifically designed for such situations.

Ok. Is 145.53.43.100 your server's IP address? From your screenshot it lokks like the IP address is 192.168.1.252. I guess 145.53.43.100 is your router's public IP address. Do you forward port 25 from your router to your ISPConfig system?

my server ip is 192.168.1.252, it's in a lan network with a router. The router's public IP address is 145.53.43.100.
And i'm forwarding port 25 tcp and udp to my server. I'm forwarding all the other ports too, like 80, 81, 21, 22 and so on.